In this letter, a general approach is proposed and conceptually designed for a single-stage and a lattice type multi-stage photonic crystal Mach–Zehnder interferometer (PC-MZI) optical filters. Accordingly, new symmetric and asymmetric PC-MZI structures based on hexagonal photonic crystal have been utilized and demonstrated to manage wavelength specifications, such as central wavelength, passband width, and bandwidth. The simulation results show that 1- and 3-dB bandwidths can obtain about 29.6 and 51.2 nm for the single-stage, 8.1 and 14 nm for the two-stage, and 3.3 and 5.76 nm for three-stage PC-MZI, respectively. Furthermore, it is observed that by combining one additional stage to single-stage PC-MZI, the passband and skirt become flattened and sharp, respectively, and in addition, a 3-dB bandwidth is reduced by 365% and 888% for two- and three-stage PC-MZI, respectively. Finally, it is shown that the single-stage PC-MZI is a wideband filter, whereas the multi-stage is a narrowband filter.